1. Field of the Invention
The present invention relates to an image analysis method and an image analysis apparatus.
2. Description of the Related Art
A technique for an image analysis called fluorescence cross-correlation spectroscopy (FCCS) has heretofore been known. The FCCS is shown in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2007-093277. According to the FCCS, excitation light is continuously applied to one or more measurement points in a sample for a given length of time (e.g. for 10 seconds), and fluctuations of the intensity of fluorescence emitted from the measurement points are detected and correlatively analyzed to estimate the number of molecules and a diffusion constant.
A technique for an image analysis called a raster image correlation spectroscopy (RICS) has been also known. The RICS is shown in, for example, “Measuring Fast Dynamics in Solutions and Cells with a Laser Scanning Microscope”, Michelle A. Digman, Claire M. Brown, Parijat Sengupta, Paul W. Wiseman, Alan R. Horwitz, and Enrico Gratton, Biophysical Journal, Vol. 89, P 1317-1327, August 2005. According to the RICS, one or more frames of raster scan images are acquired. The raster scan images may be, for example, fluorescence images. Data regarding each pixel of the fluorescence images represents information on the intensity of fluorescence generated from a point in a corresponding sample. The data regarding the pixels vary in the time and position of acquisition.
Correlation characteristics dependent on the fluctuations of molecules are obtained by a spatial autocorrelation analysis using the data regarding the pixels. A diffusion constant and the number of molecules can be found from the correlation characteristics of the molecules. A molecular diffusion time can be found from the diffusion constant.
Since the diffusion time and the number of molecules can be thus evaluated by the spatial autocorrelation analysis, an interaction between the molecules can be observed.